As a prior art of the cubic boron nitride sintered body (cBN), there is a cBN sintered body which is a sintered body where cBN particles are sintered by a binder phase, wherein the binder phase is continued in a two-dimensional view, the binder phase contains one or more selected from the group consisting of a carbide, nitride, carbonitride or boride of a transition metal of Groups 4a, 5a or 6a of the Periodic Table, a nitride, boride or oxide of Al, a carbide, nitride, carbonitride or boride of at least one of Fe, Co and Ni and mutual solid solutions thereof, a content of the cBN is 45-70% by volume, an average particle size of the cBN particles is 0.01 or more and less than 2.0 μm, an average value of a thickness of the binder phase is 1.0 μm or less, and its standard deviation is 0.7 or less (see Patent literature 1.).
Also, there is a sintered cBN compact which is a cubic boron nitride (cBN) sintered compact for a tool, comprising (a) about 60 to 80% by volume of cBN having a volume average particle size of about 3 to 6 μm, (b) about 40 to 20% by volume of a ceramic binder phase, (i) about 20 to 60% by volume of which comprises one or more of a carbide, nitride or boride of a Group IVB or Group VIB metal and (ii) about 40 to 80% by volume of which comprises one or more of a carbide, nitride, boride or oxide of aluminum, and (c) about 3 to 15% by weight of tungsten (see Patent literature 2.).